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Full set of Notes with Fill-Ins - San Jose State University

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Chem 155 Unit 5 Page 110 <strong>of</strong> 316In single photon counting:Accept only those pulses originating at thephotocathode.RetainsignalRejectnoiseRecall: Detection limitS MIN = S BLANK + 3σ BLANKLarge and small pulses are all noise!These contribute to both S BLANK and σ BLANK !Limitations to the PMT and to single photon counting:1. Wavelength limitations:Same as phototube - hν ≥ φ2. Intensity limitations:In general, the PMT is used inLOW LIGHT ONLY – ambientlight will destroy the tube.In Single Photong Counting,light levels must be lowenough that light pulses donot pile up or overlap.Page 110 <strong>of</strong> 316

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